When Tom Sedor first heard about Northampton Generating Co.'s bid to increase its lead emissions, he immediately thought of his autistic grandson.

But it wasn't long before Sedor discovered three others in his Northampton neighborhood who struggled with the disorder.

And when Sedor finally met borough resident Rose Mary Rossner, whose own tally found four people with autism near her home, the two couldn't help but wonder if there is a connection between lead emissions and autism.

Rossner plans to pose that very question on Tuesday during a public hearing on the power plant's proposal to increase lead emissions by 21 times its current level. The hearing, hosted by the state Department of Environmental Protection, is slated for 6 p.m. at the Northampton Community Center.

Northampton Generating, at 1 Horwith Drive in Northampton, is a 112-megawatt facility that burns coal waste and tires, among other fuels, to create electricity.

It wants to increase its lead emissions from the current limit of 0.0027 to 0.059 pounds per hour, a level that remains well below the U.S. Environmental Protection Agency's acceptable limit. The company deferred all comment about the permit to the DEP.

A Harvard University researcher says residents aren't being alarmists in raising concerns.

Marc Weisskopf, associate professor of environmental and occupational epidemiology at Harvard's School of Public Health, has been a part of two studies that show that pregnant women exposed to high levels of air pollution, including heavy metals like lead, had a greater risk of bearing children who develop autism.

The first study, published in December, examined the children of nurses who participated in a national, long-term study that began in 1989.

Weisskopf's study surveyed women on whether they had a child diagnosed within the autism spectrum disorder and then tracked their exposure to air pollution based on EPA data for the areas in which they lived.

The analysis examined the effects of lead, diesel, manganese, cadmium, methylene chloride and nickel on the pregnant women's fetuses. The study showed that perinatal exposure to diesel particulate matter, lead, manganese and nickel increased the likelihood of a the baby being diagnosed with autism.

A second study, published in March, didn't single out lead in particular, but examined pregnant women's exposure to particulate matter air pollution and the likelihood that their babies would develop autism. That study found the link between exposure and autism was strongest during a mother's third trimester of pregnancy.

Weisskopf emphasized there are many contributing factors that can lead to the development of autism and not all are well understood. But the correlation of air pollution exposure and autism were too significant to be ignored, he said.

"This is one contribution to it," Weisskopf said. "And it's a strong one so that's why we're pursuing this."

DEP's public hearing grew out of concerns over increased exposure to lead raised by residents, Northampton Borough Council and the Northampton Area School District. Five schools are within a mile of the plant.

Colleen Connelly, a DEP spokeswoman, said Northampton Generating is seeking to increase its lead emissions' limit because the tires it is burning create higher levels.

Northampton Generating exceeded its current lead emissions limit of 0.0027 pounds per hour on two occasions, once in 2012 and the other in 2013.

Connelly said the amount request — to 0.059 —— does not represent what the company would realistically be putting into the atmosphere.

"We don't anticipate they're even going to get near there," Connelly said. "But just in case, they do have an overrun, they have room to work with."

Connelly also said that the requested level is far below what EPA considers unsafe.

The EPA limits safe lead emissions to 0.15 micrograms per cubic meter of air, according to Connelly. She said Northampton Generating Co.'s new permit would put them at a maximum of 0.00122 micrograms per cubic meter of air.

But residents worry that the EPA's standards don't take into consideration the latest science such as Weisskopf's two studies.

Connelly said she's aware of the concern about the permit, but noted that the DEP will have to make its decision based on law and available science.

"It's frustrating but we have to rely on the evidence that we have, not speculate," Connelly said.

EPA tightened standards for lead emissions in 2008 after research pointing to the toxicants' effects on the neuro-cognitive effects on children became more clear.

In 2014, the agency voted to maintain the 2008 levels which the organization said provides adequate protection for lead emitted into the air.

The most recent research on the matter, including the two studies Weisskopf worked on, would be considered in the next batch of reviews in 2019, according to the EPA.

Weisskopf said the EPA's practice of reviewing science on the topic when setting limits is a good thing as long as the science keeps coming.

"In the long term, we need to get as much science as possible to back this up so the EPA has as much information as possible to decide whether to reduce limits," he said.

With EPA's current standards, environmentalists say residents are in an uphill battle.

"We can't count on the DEP to do anything but rubber stamp this," Mike Ewall of the Energy Justice Network, a grass-roots organization, said. "The best line of defense is for the borough to pass an air law to protect its residents."

Ewall said he's worked with three other municipalities throughout the state that did just that. And in Kulpmont, Northumberland County, the municipal law held up against a federal court challenge.

Sedor said he's resolved to keep up the struggle should Ewall's prediction prove right.

"You can fight city hall sometimes," Sedor said of challenging the status quo. "There is a light at the end of the tunnel. I'm not going to give up this fight."

•The DEP is holding a public hearing at 6 p.m. Tuesday at the Northampton Community Center, 1601 Laubach Ave., on Northampton Generating Co.'s request to increase lead emission levels from 0.0027 pounds per hour to 0.059 pounds per hour.